Printing telegraph system



Sept. 30, 1941. c. GOODWIN' PRINTING TELEGRAPH SYSTEM Filed Jan. 9, 19402 Sheets-Shea*l l tot E. .En 5.1mm

' /NVE/VTOR C .GOODWIN ATTORNEY Sept. 30, 1941. c. GooDwIN 2,257,677

` PRINTING TELEGRAPH SYSTEM Filed Jan. 9, 1940 2 sheets-sheet 2 .mmm BwNGN QQN Patented Sept. 30, 1941 PRINTING TELEGRAPH sYsTEii/i ClaytonGoodwin, Denver, Colo., assignor to American Telephone and TelegraphCompany, a corporation of New York Application January 9, 1940, SerialNo. v313,111

11 Claims.

This invention relates to a communication system for transmitting signalimpulses over telegraph lines or channels of toll lines and moreparticularly to a telegraph system for connecting an outlying linetelegraph subscribers station to a central switching office over atelegraph line or channel.

A telegraph system of this character permits the extension of telegraphlines each of which may be connected to a plurality of subscribersstations, in parallel.

An object of the invention is to permit a plurality oi` subscribersstations connected to a line to be extended to a repeater station which,in turn, is connected to a central oice.

Another object of the invention is to lock out,

, scribers line `circuit equipment at the teletypeor prevent, onesubscribers station from using a line when another subscribers stationis operatively connected to the same line.

According to the present invention, a plurality of subscribers stationsmay be connected to a toll line extension circuit that extends from adistant telegraph exchange oilice through a. distant repeater station.Each of the subscribers stations is equipped with a teletypewriter setcomprising a source of alternating current, a low voltage rectifier anda switch for connecting the alternating current source to the primarywinding of a high voltage transformer. Connected to the secondarywinding of the high Voltage transformer is a full wave rectifier, theoutput of which serves to operate a connector relay, a busy lamp and alock-out relay. When the connector relay operates, a control wireoperatively connects one station with the other stations whereby agrounded circuit is completed to operate the busy lamp andlock-out relayat each of the other stations so that the subscribers at the otherstations are prevented from establishing a connection to the exchangeoilice when one of the stations is busy.

A feature of the invention is the use of a control circuit in additionto the message circuit, between the subscribers stations connected tothe line and a lock-out relay ateach of the subscribers stationsconnected to put the line on a non-seizure basis.

The invention will now be described with respect to the accompanyingdrawings which illustrate a telegraph exchange system to which anembodiment of the invention may be satisfactorily adapted. The drawingsare arranged into two figures:

Figure 1 shows a distant teletypewriter exchange ofdce equipped on oneside with a teletypewriter subscribers station and on the other sidewith a toll line extension circuit extending through a repeater stationat a distant point to a lineto which two subscribers stations areconnected in parallel. l

writer exchange oiiice. The equipment at the subscribers station A andat the termination of line |04 may be similar to that shown in Fig. 5 ofUnited States Patent 2,143,000, granted to W. W. Cramer et al. onJanuary 10, 1939. Line |04 may be one of a plurality, as shown,terminating at the switchboard at station A.

By means of the operators cord circuit |06 and the operators positioncircuit |01, the subscribers line |04 may be extended over a toll lineextension circuit including jack |08, repeater |09, single conductortoll line H0. The repeater |09 may be located at a point distant fromthe exchange oflice. The operators cord circuit |06 and the operatorsposition circuit |01 may be similarto those respectivelyshown in Figs. 3and 4 of United States Patent 2,143,000, supra. The terminatingequipment connected to jack |08 at the exchange oice may be similar toFig. 8 of United States Patent 2,143,000, supra. The repeater |09 may besimilar to that shown at the left side of Fig. 7 of United States Patent2,143,000, supra.

The single conductor toll line 0 terminates in two or more parallelpaths 20|, 20|', etc., respectively extending to stations X, Y, etc.`'I'he equipment at stations X and Y is identical. A description of theequipment at station X should suice ior a description of that at stationY. Corresponding parts of the equipment at stations X and Y willhereinafter beldesignated by like reference characters except that thepart at station Y will be further designated with prime marks. Thecircuit including conductor 20| may be traced through the contact andoutermost armature of lock-out relay 202 to ground atsubscribers'teletypewriter set 203. The teletypewriter set 203 issimilar to that shown in Fig. 1 of United States Patent 2,143,000,supra, and is energized from an alternating current source 204. Powersource 204, in response to the operation of a power switch in theteletypewriter set, energizes theprimary winding 205 of a transformer inaddition to energizing the teletypewriter motor, the rectifier and thestart relay (the latter two not shown) of the teletypewriter set asdescribed in United States Patent 2,143,000, supra, page 3, undercaption Subscriberoriginates a call. l

A full-wave rectiiier tube 206 obtains its cathode current fromsecondary winding 201 and plate currents froml secondary winding 208 ofthe transformer. Connected across the output of the tube is a ltercomprising inductance 280 and condenser 2l0 to smooth out any ripplesthat may be in the rectified alternating current. The positive side ofthe output circuit is connected to busy lamp 2 I l and the winding oflock-out relay 202, in parallel and to connector relay 2|3. The negativeside is connected through resistance 2l2, middle armature and contact ofrelay 202 tothe front contact and winding of relay 2l3. When rectifiertube 206 is energized, the current flows in the output circuit through.resistance 2| 4 of comparatively high value and the Winding of relay2|3. The relay operates to connect a control wire .2l5 to its irontcontact.

Method of operation The system will now be described from the viewpointof originating a call at station X. The subscriber at station Xoperatesthe power switch (included in the teletypewriter set 2-ii3) to energizerectifier tube 206 and, in turn, connector relay 213.r Rectified currenttherefore iiows from the negative side of the outputA circuit of tube2%, through resistance 212, middle armature and contact of lock-outrelay 2ll2, front contact and armature of relay 2l3, control wire 2|5 tostation Y where it extends over armature and back contact on 'connectorrelay 213', then over parallel paths, one through the winding oflock-out relay 202', and the other through lousyv lamp 2H to thegrounded positive side of the output circuit of tube 206. Busy lamp 2| Ilights and lockfont relay 202 operates. The lighting of `lamp 2Hindicates to the subscriber at station Y that the toll line H0 is busyand relay .2532', upon operating, opens the normally closed contacts atits middle armature to prevent seizure of the line by the subscriber atstation Y When the line is engaged by the subscriber at station X.

Assume that station X is operatively connected to line HiL'busy lamp 2|I at station Y is lighted and relay 202" at station Y is operated. Nowassume that the power switch of subscribers teletypewriter set 203' isoperated,- then rectier tube 206' becomes energized. Accordingly,currentmwill flow from the positive side of the output circuit of tubeV206', through resistance 2id and the winding of relay 2l3 and back tothe negative side of the output circuit. Relay 253' will operate butwill not upset the circuit condition previously established. The controlcurrent from. tubeZS at station X will continue to tion X is operativelyconnected to the line circuit and theV subscriber at stationY awaitsi'anopportun-ity to get the line. Alsoassurne that thesubscriber atstationXrwishes to recall the operator by restoring the power switch inteletypewriter set 203l for a short interval. If'the power switchat'teletypewriter set 203 at station Y has been in its operatedpositionfora time suijcient to energize the reetiiertubev 206', then the momentthat the power switch at set 203 is restored, relay 202' at station Ywould release and the subscriber at station Y would seize they linecircuit and the teletypewriter set 203 at station X would be locked out.This will not occur in polarential systems wherein the spacing signalvoltage at the end where the polar signals are received, is of the samepolarity as the marking signal voltage at the opposite end. However, insystems wherein the spacing signal voltage at the polar receiving end isof the opposite polarity to the marking signal voltage at the other endand wherein the above-mentioned objection may exist, the manual recallfeature is employed whereby the line circuit itself is opened for ashort interval of time to send a recall or flashing signal and there isno need of opening the power circuit of the teletypewriter set.

Call originating at the exchange oce On a call incoming at one of thetwo stations X and Y, coded ringing may be provided since the ringers,or call bells will ring. The `ringers are shown in Fig. 1 of UnitedStates Patent 2,143,000, supra. Ordinarily the code used will be onering for station X and two rings for station Y.

Special Operating 'feature for subscriber When a called signal isreceived at the switchboard at the exchange office from a toll linecircuit havingltwo stations connected to it, the

operator will be unable to distinguish at which station, operable means,normally deenergized,

at each of said'stations for causing the seizure of said channel forcommunication purposes to the exclusion of the remaining of saidstations.

2. In a telegraph switching system having a single telegraph centraloiice, a multiparty single telegraph line extending from said office toa pluralityof subscribers stations, means whereby an operator .may callanyof said stations, means for setting any called station into comemunicative relation to the central office over said line, lock-out meansin each station and means controlled by setting any one of said stationsinto communication relation to actuate said lock-out means to prevehtlall but said called one subscriber station fromY being conditioned forcommunicative relation inV response to the operation or" the settingmeans at said called subscribers station. A Y Y l,3. A telegraph systemcomprising a main' station and a source of signals thereat, a pluralityof stations, a line circuit connecting said stations'torsaid mainstation, signal means at each ofsaidjstations respon-sive to signalsfrom said source; operable `start switch in each of said stations forseizingv said line circuit for communication purposes, and means at eachof said stations responsive to the operation of said operable switchatfany one of'said stations for preventing theremaining of Vsaidstations from seizing saidrlinetcircui-t y.when said linel circuit isseized by said one station'. Y

4. A telegraph system comprising. tion anda source of signals thereat, aplurality indicating at only the remaining of said stations that saidone of said stations has seized said line circuit.

5. A telegraph system comprising a teletype writer exchange oice, aplurality of teletype--` writer stations, a normally deenergized linecircuit connecting said stations to said teletypewriter exchange oiiice,a starting switch at each of said stations, said starting switch -at anyone of said stations arranged, when operated, to operatively connectsaid one only of said stations to said line circuit for telegraphiccommunication purposes to the exclusion of the remaining of saidstations.

6. A signaling system comprising a signal` transmission circuit, aplurality of stations normally connected unoperatively to said circuit,a source oi alternating current at each of said stations, a start switchcooperating with each of said sources for operatedly connecting saidtransmission circint to one of said stations,` a converting meansconnected to each of said sources and a grounded output circuittherefor` capable, when its associated start switch is operated, ofproducing a voltage of steady amplitude, a switching element at each ofsaid stations responsive to the voltage of steady amplitude, a controlcircuit interconnecting said stations, and adapted to switch in responseto the operation of said switching element at any one of said stationsfrom one to the other polarity of the output circuit at said onestation, and means at said other station responsive to the switching ofthe polarity of said control circuit at said one station for furnishingan indication that said one station is operatively connected to saidtransmission circuit.

7. A switching system comprising a signal transmission circuit, aplurality `of stations normally connected unoperatively to said circuit,a`

source of alternating current at each of said stations, a start switchcooperating with each of said sources for operatively connecting saidtransmission circuit to one of said stations, a rectifying meansconnected to Veach of said sources and a grounded output circuittherefor capable, when its associated start switch is operated, ofproducing a direct current Voltage, a switching element at each of saidstations responsive to the direct current voltage, a control circuitinterconnecting said stations, and adapted to switch in response to theoperation of the switching element at one of said stations from one tothe other polarity of the output circuit at said one station, means atsaid other stations responsive to the switching of the polarity of saidcontrol circuit at said one station for furnishing an indication thatsaid one station is operatively connected to said transmission circuit,and other means in said other stations responsive to the switching ofthe polarity of said control circuit at said one station for preventingsaid transmission circuit from being operatively connected to any one ofthe other of said stations during the time that said transmissioncircuit is operatively connected to said one station.

8. A teletypewriter system comprising a signal transmission circuit, aplurality of stations nor- -mally connected to said circuit, ateletypewriter set including a low voltage rectiner and a source ofalternating current therefor at each of said` stations, saidteletypew'riter set being normally connected unoperatively to saidtransmission circuit, a high voltage rectier responsive to each o' saidsources, a start switch for operatively connecting each of said sourcesto its associated i low voltage and high voltage rectiers, a groundedoutput circuit for each of said high voltage rectiers capable, when itsassociated start switch is operated, of producing a direct currentvoltage, an electro-magnetic relay at each of said stations responsiveto the direct current: voltage, a control circuit interconnecting saidstations and adapted to switch in response to the i operation of theelectromagnetic relay at one of saidstations, from one to the otherpolarityof the output circuit at said one station, a lamp at each ofsaid other stations responsive to the switching of said control circuitat said one stationfor furnishing an indication that said telctypewriterset at said one station is operatively connected to said transmissioncircuit, and another electromagnetic means at said other stationsresponsive tothe switching of the polarity of said control circuit atsaid one station for preventing the teletypewriter set at each saidother stations from being operatively connected to said transmissioncircuit during the time that said transmission circuit is operativelyconnected to the teletypewriter set at said one station.

9. In a teletypewriter exchange system a` central omce, a plurality ofoutlying stations, a normally deenergized transmission channelinterconnecting said central oiiice and said outlying stations, a sourceof signals at said central oiiice and each of said outlying stations,signal means at each oi said outlying stations responsive to signalsfrom said source at said central office,`

manually operable means at each of said outlying stations, andenergizing means at said outlyi ing stations responsive to said operablemeans at any one of said outlying stations for operatively connectingone of said outlying stations to said transmission channel and fordisconnecting the other of said outlying stations from saidtransmission-channel during the time that said one station isoperatively connected to said` transmission channel.

lil. In a telegraph system, a central oilice, a i

CLAYTON GOODWIN.

DISCLAIMER 2, 257, 677 .-Olayton Goodwin, Denver, Colo. PRINTINGTELEGRAPH SYSTEM. Patent dated September 30, 1941. Disclaimer filedApril 17, 1943, by the assignee, American Telephone and TelegraphCompany.

Hereby enters this disclaimer to claims 2, 3, and 4 of said patent.

[Ojcial Gazette May 18, 1943.]

